JP3260217B2 - Method and apparatus for measuring powder particle size - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the particle size of powder, and more particularly to a measuring method and an apparatus suitable for measuring the particle size of granulated powder such as cemented carbide and cermet used in powder metallurgy. .

[0002]

2. Description of the Related Art Conventionally, there are methods for measuring the particle size of powder particles using various principles, but in particular, a sieving method using a mechanical method using a mesh, a sound wave, a mechanical vibration, or the like, a visible light method, or the like. A measuring method by an optical method using a laser, an X-ray, or the like has been used.

[0003] The optical measurement method is such that, when an aggregate of powder passes through a measuring section, light such as visible light, laser beam, or X-ray is applied from one side, and at a certain moment, the light is received on the opposite side. It analyzes and detects the particle size of the powder. Of the optical measurement methods, the wet method, which has become the mainstream in recent years, is a method of measuring the particle size in a state where powder is dispersed in a solvent, and it is a measurement of each lot compared to a mechanical method such as a sieving method. A large amount can be obtained, and the particle size range that can be measured is wide.

[0004]

However, any of the above-described conventional particle size measuring devices is suitable for measuring hard raw material powders, but various problems occur when applied directly to the particle size measurement of granulated powders. This is because the powder obtained by wet-mixing the raw material powder and spray-drying the granulated powder has a softer surface than the raw material powder and is more likely to be broken or agglomerated.

[0005] Therefore, when the sieving method of the mechanical method is used, the granulated powder is crushed by sound waves or mechanical vibrations at the time of passing through a mesh or at the time of measurement, so that an accurate particle size cannot be measured.

[0006] Even when a wet method using laser light is used, the true particle size cannot be measured due to the collapse or aggregation of the granulated powder in a solvent. Even in a dry method in which a sample is transported to a measuring section by vacuum suction without using a solvent, the granulated powder is poorly dispersed and is transported in an aggregated state, so that it has been difficult to measure an accurate particle size.

[0007]

Means for Solving the Problems The present inventors have solved the above-mentioned problems in measuring the particle size of granulated powder of a hard alloy, and studied how efficiently and accurately the granulated powder can be measured. This has led to the present invention.

According to the present invention, there is provided a method for measuring the particle size of a granulated powder comprising a cemented carbide, a cermet or a ceramic by an optical method such as laser or X-ray. Then, a method in which a gas such as air or nitrogen is blown immediately before the measurement to disperse the powder is adopted.

[0009]

First, an optical method such as laser or X-ray is used for particle size measurement in view of the measurement efficiency and accuracy. or,
If the wet method of dispersing a sample in a solvent is used, the granulated powder having a soft surface is deteriorated. Therefore, the granulated powder is dropped in a dry state, and the measurement is performed in the middle.

A plurality of granulated powders are weakly agglomerated and 2 to 5 mm
It is a mass of about, and if it is carried to the measuring part as it is, accurate particle size can not be detected, so before falling for measurement, vibration is applied to the granulated powder to disperse and disperse it, This vibration may be ordinary mechanical vibration supplied by driving a motor or the like.

Further, a gas such as air or nitrogen is blown onto the granulated powder that has just dropped and is just before the measurement. If the dispersion is performed by blowing gas, the granulated powder having a soft surface can be dispersed into individual particles without damaging the powder, and accurate particle size measurement can be performed.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

[0013] The granulated powder of the cemented carbide was mixed with WC-5% Co, wet-mixed, dried and granulated by a spray drier, and the particle size was measured by the method of the present invention.

First, a granulated powder to be measured is supplied to the guide 1. Vibration is applied to the entire guide 1,
The granulated powder in the guide 1 is sent so as to slide down diagonally downward, and falls just above the sample supply port 2. In addition, the agglomeration of the plurality of granulated powders is loosened by the vibration applied at this time.

The granulated powder 3 that falls is blown with air 5 by a gas injection device 4, and further falls while the aggregation of a plurality of particles is loosened into individual particles. 3 is irradiated with laser light by a laser light emitting device 7, a diffraction image of the granulated powder 3 is detected by a light receiving section 8, and the particle size is measured after analysis.

In addition to the examples of the present invention, measurements were also made by a conventional laser dry vacuum suction method, a laser wet method, and a sieving method as comparative examples, and the measured particle size and dispersion (R: maximum value and minimum value) were measured. Table 1 shows the results of the differences in the values.

[0017]

[Table 1]

[0018]

As described above, according to the present invention,
Since the particle size distribution of the granulated powder can be measured efficiently and accurately,
The use of the granulated powder whose particle size is adjusted by utilizing the particle size measurement has effects such as improvement of the dimensional accuracy of the pressed body and reduction of the crack failure of the cermet pressed body.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a powder particle size measuring apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Guide 3 Granulated powder 5 Air 6 Measuring part 7 Laser emitting device

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiro Minato 1-1-1, Kunyokita, Itami-shi, Hyogo Itami Works, Sumitomo Electric Industries, Ltd. (56) References JP-A-5-149864 (JP, A (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 15/14

Claims (2)

(57) [Claims] 1. A method for measuring the particle size of a granulated powder comprising a cemented carbide, a cermet or a ceramic by an optical method such as laser or X-ray, wherein the granulated powder is supplied to a measuring unit in a dry manner while applying vibration, A method for measuring the particle size of a granulated powder, comprising blowing a gas such as air or nitrogen immediately before measurement to disperse the powder. 2. An apparatus for measuring the particle size of a granulated powder comprising a cemented carbide, a cermet or a ceramic by an optical method such as a laser or an X-ray. And a device for spraying a gas such as air or nitrogen immediately before the measurement to disperse the powder, wherein the particle size of the granulated powder is measured.